In many applications there is a need for connecting or coupling together objects, such as boxes, trays, cases, cages, containers or other objects.
One such application is tending and storing of benthonic organisms, such as sea urchins, abalones, sea cucumbers, scallop shells, oysters in aquatic environment.
Such a system is described in Norwegian Patent Application NO 20030973 which is hereby incorporated in this specification by reference.
Another application is cases or boxes for transporting and or storing items. In order to be able to stack the boxes efficiently and/or to move several boxes in one operation, it is preferable that they are safely and rigid connected to each other.
Also for construction elements there is a need for securely connecting the elements, such as provisional or permanent walls and floors, parquet floors, form elements etc.
NO 128862 shows an example on a prior art case for transporting fish which can be stacked. The case is made of plastic and has guiding grooves on the upper side and projections with trapezoidal shape in the base portion. The grooves and base projections are narrower in the middle than at the end portions, and this means that when the base projections are inserted sliding into the grooves, they will lock to each other by means of friction.
This connecting mechanism depends on the friction forces to keep the cases together. This will not be sufficient for many applications where it is important that the cases or other connected objects are securely connected even when influenced by external forces. It is for example very important that the tending/storing cases described in NO 20030973 are securely connected when immersed in the sea where they will be influenced by e.g. currents, tides, wind, etc. There is also no way to ensure that the cases are securely connected before transporting, handling or other use of the connected cases and there exists a risk that the cases will disconnect unexpectedly.